As this table from Bob’s report illustrates, the cost of development of the SLS/Orion is enormous:

Furthermore, an operational SLS/Orion will only launch once every year or two. So with an annual budget of $2B or more, that means each launch will cost at least $2B, not counting the above development costs. (Often NASA officials will quote something in the range of $500M per launch but this is a mythical “marginal” cost number that includes only what was paid for fuel, metals, etc. for one rocket, not the full expense required to make the launch happen.)

Meanwhile, SpaceX has already pushed launch costs 2-3 times lower for NASA and commercial satellite customers compared to a few years ago. And SpaceX, Blue Origin and others are developing reusable launch systems and spacecraft that will dramatically lower the cost of getting to space below today’s prices.

The SLS rocket was forced on NASA by Congress (or more accurately by the space policy and budget committees dominated by Senators and Representatives of states and districts with NASA centers and major contractors), which actually dictated most of the design of the all-throwaway rocket.

The money saved by dropping SLS/Orion and instead flying on competitively sourced commercial space transport services could be redirected by NASA to develop crucially needed space technologies such as in-space tugs, propellant depots, lunar and asteroid mining and manufacturing systems, rotating habitats to provide spin-gravity, etc. These technologies are required to make travel beyond earth affordable and space settlement feasible.

Here is a video preview of Blue Origin’s New Glenn, which will start flying in 2020 (a factory to build the New Glenn is under construction on Cape Canaveral):

And here is a NASA video from an interview with Dan Rasky, who worked as a Senior Scientist for NASA on the Commercial Orbital Transportation Systems (COTS) program, talking about how SpaceX built the Falcon 9 for a factor of 10 less than the NASA/USAF procurement cost model said it should cost (and the model usually underestimates aerospace project cost):